Reciprocation engine exhaust scavenging system

ABSTRACT

An exhaust gas scavenging apparatus includes a series of chambers designed to actively lower the exhaust gas back pressure of an internal combustion engine. The device uses the waste energy from the exhaust system in the form of both the Venturi principle and the amplification of a pulse wave effect. The scavenging system uses a series of in-line tubes or a single tube with perforations, passing through multiple sealed chambers using the Venturi effect to lower the pressure in each chamber.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. provisional application No. 62/397,114, filed Sep. 20, 2016, the contents of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to exhaust systems, and more particularly to exhaust scavenging systems for reciprocating engines.

Internal combustion reciprocating engines by the nature of their design produce large amounts of unused energy that is expelled in the form of the waste gases. Harnessing this energy and putting it to use would thereby increase the overall efficiency of the engine.

Reciprocating internal combustion engines by design are generally restricted to a very short period of time for cylinder evacuation. After initial blow down of the cylinder the engine then consumes a portion of its generated energy to push the burn gases out of the cylinder as the piston moves up. By lowering the pressure ahead of the gases they move out of the cylinder more easily and reduce the pumping energy required by the engine. The design of this device uses each exhaust pulse to create a low pressure zone ahead of the next pulse which effectively reduces the pressure at the exhaust port.

The internal combustion engine acts fundamentally as a mechanical pump. It draws in air and pushes the air out, any reduction in resistance of air flow directly reduces the amount energy required to pump the air. In operation this invention uses the kinetic energy of the blow down pulse to create a low pressure zone for the next blow down cycle causing a reduction in the required pumping force.

A full evacuation of the combustion cylinder is desired to reduce contamination of the incoming fuel air charge. Creating a lower pressure at the exhaust port reduces the level of contamination remaining in the chamber.

A common practice is to use tubular headers with a collector, “Y” and “X” pipes to produce this effect on high revving, high performance engines. These systems tend to be expensive, work only at higher RPM, are difficult to package in normal applications, and only produce 1 stage of scavenging.

As can be seen, there is a need for an improved exhaust gas scavenging system to harness the kinetic and pressure energy available in the exhaust flow to power an induction pump with no moving parts. This use of waste energy increases total performance and engine energy efficiency.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an exhaust gas scavenging apparatus for an internal combustion engine, includes a plurality of sealed interconnected chambers, each chamber having at least one outer sidewall and an end wall to define a cavity therein. A plurality of in line tubes pass through the plurality of sealed chambers and are interconnected along a length of the exhaust gas scavenging apparatus. The plurality of in line tubes are configured to receive an exhaust gas flow from the exhaust of an internal combustion engine and communicate the exhaust gas through the plurality of sealed chambers. Each of the plurality of in line tubes have a sidewall, an inlet and an outlet, the inlet having a larger diameter than the outlet, wherein the sidewall converges inwardly along a length of the tube to define a Venturi constriction proximal to the outlet. The outlet of a preceding in line tube is received within the inlet of a subsequent lined tube.

The exhaust gas scavenging apparatus may also include a Venturi opening formed between the outlet of the preceding in line tube and the inlet of a subsequent in line tube. The Venturi opening may be formed within each of the plurality of sealed chambers. The end walls of the chamber are sealed around the sidewall of the in line tubes, preferably around an intermediate portion of each in line tube. In some embodiments, the Venturi opening is located at an intermediate position within the plurality of sealed chambers.

In other embodiments, an exhaust gas scavenging apparatus for an internal combustion engine includes a plurality of sealed interconnected chambers, each having at least one outer sidewall and an end wall to define a cavity therein. An in line tube is carried through the plurality of sealed chambers, with the in line tube configured to receive an exhaust gas flow from an exhaust of the internal combustion engine and communicate the exhaust gas flow through the plurality of sealed chambers. A Venturi constriction is defined in the in line tube in each of the plurality of sealed interconnected chambers and a Venturi opening is defined at an end of the Venturi constriction. The Venturi opening is configured to communicate an exhaust gas pulse between the cavity and an interior of the in line tube.

In some embodiments a single tube with a plurality of perforations is used to create the venturi for each of the sealed chambers. The perforated tube is aligned within each sealed chamber so that a series of sidewall perforations aligned to the downstream most portion of each sealed chamber. The perforations in this embodiment represent the Venturi openings. The chamber side wall is sealed to the next chamber and the end wall of each chamber is sealed around the sidewall of the perforated tube creating a cavity. The Venturi opening may also be located at an intermediate position within the plurality of sealed chambers.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional diagram of a Short in-line tube embodiment of the exhaust scavenging apparatus.

FIG. 2 is a cross sectional diagram of perforated tube embodiment of the exhaust scavenging apparatus.

FIG. 3 is a cross sectional diagram illustrating a method of constructing a short in-line tube exhaust scavenging apparatus.

FIG. 4 is an exploded cross sectional diagram of perforated tube embodiment of the exhaust scavenging apparatus.

FIG. 5 is a 3 dimensional representation of a cross sectional diagram of perforated tube embodiment of the exhaust scavenging apparatus.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Broadly, embodiments of the present invention provide an exhaust system with a series of chambers designed to actively lower the exhaust gas back pressure in an internal combustion engine. The device uses the waste energy from the exhaust system in the form of both the Venturi principle and the amplification of a pulse wave effect. The scavenging system uses a series of in-line tubes or a single tube with perforations, passing through multiple sealed chambers using the Venturi effect to lower the pressure in each chamber.

Each exhaust pulse, when passing through the device, is able to multiply the intensity of its own trailing low pressure and reduce the pressure ahead of a subsequent exhaust pressure pulse produced by the engine. The leading pulse is coupled to the trailing pulse by the low pressure zone between the two pulses. The inertia from the leading pulse enables it to continue its direction of flow while the trailing pulse is accelerated or drawn into the low pressure zone between the two pulses. The net effect is that every pulse that passes through the system lowers the resistance for the subsequent pulse until equilibrium is achieved. The resulting action of the exhaust scavenging device is to increased engine performance through increased cylinder exhaust scavenging, reduction of exhaust gas back pressure and increased engine volumetric efficiency.

As seen in reference to FIGS. 1 and 2, an embodiment of an in-line tube exhaust gas scavenging apparatus includes a plurality of in line tubes 1 that pass through a plurality of sealed chambers 2 that are interconnected along a length of the apparatus. The sealed chambers 2 include at least one outer sidewall 7 and an end wall to 8 define a cavity therein. The in line tubes 1 are configured to receive an exhaust gas flow 4 from an internal combustion engine and pass it through the plurality of sealed chambers 2.

The in line tubes 1 have an inlet 9 and an outlet 10, wherein the inlet 9 has a larger diameter that than the outlet. The sidewalls of the in line tubes 1 converge inwardly along a length of the tubes 1 from the inlet 9 to the outlet 10 to form a Venturi constriction at a junction between the respective tube elements 1. The in line tubes 1 are interconnected such that the outlet 9 of a preceding in line tube 1 is received within the inlet 10 of a subsequent lined tube 1. A Venturi opening 3 is formed at a gap between the smaller diameter outlet 9 of the preceding tube 1 and the larger diameter inlet 10 of the subsequent in line tube 1. The end walls 8 of each sealed chamber 2 are sealed around a circumference of the sidewall of the in-line tubes 1.

As seen in reference to FIGS. 3-5, illustrating a perforated tube embodiment of the exhaust scavenging apparatus, an elongate length of tube 11 has a plurality of tube perforations 12 that are defined in a spaced apart relation around a circumference of the elongate tube 11. The sidewalls of the elongate tube 11 is constricted at the plurality of perforations 12 to convergee inwardly from an inlet end 14 of the elongate tube and an outlet end 15 of the tube, forming Venturi inlet 13. A sidewall 16 and an endwall 15 define the plurality of chambers 18.

Each chamber 2, 18 of the device is able to create a drop in pressure 5 as an exhaust blow down pulse 4 passes through and a volume of trapped air contained within the plurality of chambers 2, 18 is drawn out of the sealed chambers 2 via the Venturi inlets 3, 13. By using multiple chambers 2, 18 in sequence, a greater reduction in pressure is achieved. Given that the blow down pulse 4 has both mass and kinetic energy, it will continue to travel down the exhaust system while pulling against the low pressure it has generated behind it. The next blow down pulse 4 generated by the engine will attempt to accelerate into the low pressure area ahead of it, thereby increasing its speed. The increase in speed also increases the Venturi effect on each of the chambers 2, 18 as this secondary pulse passes through causing a greater drop in pressure 5.

The system of the present invention installs in-line with an exhaust system as a muffler type device, which can work as low as idle speeds on multiple cylinder engines and may have multiple stages of scavenging in a small relatively inexpensive package.

As seen in reference to FIGS. 1 & 2, embodiments of the apparatus may be formed by forming a plurality of chamber segments with chamber portion 2 having a cylindrical sidewall 7 and an end wall 8. The end wall 8 may be attached to the sidewall 7 via a weld, or the component may be formed to the desired shape via a press. The inline tube segment 1 is inserted into an aperture defined in the end wall 8 and sealed, via a close fitting engagement of the tube segment 1, more preferably a weld. The open ends of the chamber segments 2 may be fitted with a preceding chamber segment and welded along an outer diameter of the union between the sidewalls 7 and an outlet end of the preceding segment. At the inlet end, an end plate 6 is formed for attachment to seal the open end of the first stage chamber segment. The inlet tube may have substantially parallel sidewalls, without the converging sidewalls. The inlet tube and the outlet of the last stage are dimensioned to fit in-line with the exhaust system pipes of the internal combustion engine.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. 

What is claimed is:
 1. An exhaust gas scavenging apparatus for an internal combustion engine, comprising: a plurality of sealed interconnected chambers, each having at least one outer sidewall and an end wall to define a cavity therein; a plurality of in line tubes that pass through the plurality of sealed chambers, the plurality of in line tubes interconnected along a length of the exhaust gas scavenging apparatus, the plurality of in line tubes configured to receive an exhaust gas flow from an exhaust of the internal combustion engine and communicate the exhaust gas through the plurality of sealed chambers; the plurality of in line tubes each having a sidewall, an inlet and an outlet, the inlet having a larger diameter than the outlet, wherein the sidewall converges inwardly along a length of the tube to define a Venturi constriction proximal to the outlet; wherein the outlet of a preceding in line tube is received within the inlet of a subsequent in line tube.
 2. The exhaust gas scavenging apparatus of claim 1, further comprising: a Venturi opening formed between the outlet of the preceding in line tube and the inlet of a subsequent in line tube.
 3. The exhaust gas scavenging apparatus of claim 2, wherein the Venturi opening is formed within each of the plurality of sealed chambers.
 4. The exhaust gas scavenging apparatus of claim 3, wherein the end walls are sealed around the sidewall of the in line tubes.
 5. The exhaust gas scavenging apparatus of claim 4, wherein the end walls of the plurality of sealed chambers are sealed around an intermediate portion of each in line tube.
 6. The exhaust gas scavenging apparatus of claim 5, wherein the Venturi opening is located at an intermediate position within the plurality of sealed chambers.
 7. An exhaust gas scavenging apparatus for an internal combustion engine, comprising a plurality of sealed interconnected chambers, each having at least one outer sidewall and an end wall to define a cavity therein; an in line tube carried through the plurality of sealed chambers, the in line tube configured to receive an exhaust gas flow from an exhaust of the internal combustion engine and communicate the exhaust gas through the plurality of sealed chambers; a Venturi constriction defined in the in line tube in each of the plurality of sealed interconnected chambers; and a Venturi opening defined at an end of the Venturi constriction, configured to communicate an exhaust gas pulse between the cavity and an interior of the in line tube.
 8. The exhaust gas scavenging apparatus of claim 7, wherein the Venturi opening comprises a perforation through a sidewall of the in line tube.
 9. The exhaust gas scavenging apparatus of claim 7, wherein the in line tube comprises a plurality of interconnected in line tube segments each having a sidewall, an inlet and an outlet, the inlet having a larger diameter than the outlet, wherein the sidewall converges inwardly along a length of the in line tube to define a Venturi constriction proximal to the outlet.
 10. The exhaust gas scavenging apparatus of claim 9, wherein the Venturi opening formed between the outlet of a preceding in line tube and the inlet of a subsequent in line tube.
 11. The exhaust gas scavenging apparatus of claim 10, wherein the end walls are sealed around the sidewall of the in line tube.
 12. The exhaust gas scavenging apparatus of claim 11, wherein the end walls of the plurality of sealed chambers are sealed around an intermediate portion of the in line tubes.
 13. The exhaust gas scavenging apparatus of claim 5, wherein the Venturi opening is located at an intermediate position within the plurality of sealed chambers. 